Appearances of Color
Color is always and solely a sense impression, comparable with the pain one feels when pricked with a needle. The origin of a color sensation is in most cases a physical stimulus from outside which is projected as color stimulus onto the retina of the eye (exception, e.g. dreams). But this color stimulus can come into being in different ways.
The color stimulus can enter the eye directly from a source of light or indirectly via any material. If it enters the eye directly from the light source, we are speaking of chromatic light or light-color. If it reaches the eye via any material, then there are two fundamentally different options: the material could be opaque, that is non-transparent, or translucent, what is transparent.back to top